Historical ground-water-flow patterns and trends in iron concentrations in the Potomac--Raritan--Magothy aquifer system in parts of Philadelphia, Pennsylvania, and Camden and Gloucester Counties, New Jersey

Water-Resources Investigations Report 2003-4255

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Abstract

The Potomac-Raritan-Magothy (PRM) aquifer
system is an important sole-source ground-water
supply in Camden and Gloucester Counties, N.J.
Elevated iron concentrations are a persistent
water-quality problem associated with ground
water from the PRM. In Philadelphia, the PRM no
longer is usable as a water supply because of
highly elevated concentrations of iron (as high as
429 mg/L [milligrams per liter]), manganese (as
high as 4 mg/L), and sulfate (as high as
1,720 mg/L). A strongly reducing environment in
the PRM in south Philadelphia causes these constituents
to be remobilized by reductive dissolution
of the aquifer matrix.
By the 1920s, ground-water pumping changed
the natural ground-water-flow patterns, and ground
water flowed toward pumping centers in Philadelphia.
By 1940, recharge areas changed from the
topographically high areas east of Trenton, N.J., to
the outcrop area of the PRM in Philadelphia, and
the Delaware River became a source of recharge
instead of a point of ground-water discharge. By
1954, the cone of depression caused by pumping
at the former Philadelphia Naval Ship Yard (PNSY)
exceeded 50 feet below NGVD 29, and the direction
of ground-water flow was from New Jersey
toward Philadelphia. Because of highly elevated
concentrations of iron and manganese, pumping at
the former PNSY ceased in the mid-1960s. Beginning
about 1951, increased ground-water withdrawals
from the PRM in New Jersey reversed the
hydraulic gradient so that ground-water flow was
from Philadelphia toward New Jersey under the
Delaware River, making Philadelphia a recharge
area for the PRM aquifer system in parts of Camden
and Gloucester Counties. By 1988, water levels
in the lower aquifer of the PRM in New Jersey
had declined to 103 feet below NAVD 88.
In 1943, dissolved iron concentrations ranged
from 0.07 to 0.6 mg/L at the former PNSY. By 1967
when the wells at the PNSY were abandoned, dissolved
iron concentrations had reached 46 mg/L.
Dissolved iron concentrations in water from industrial
wells in Philadelphia increased from 0.17 mg/L
in 1949 to 19 mg/L in 1979. The concentration of
dissolved iron in water from wells screened in the
lower aquifer in New Jersey also increased with
time. By 1985, dissolved iron concentrations were
as high as 16 mg/L for Eagle Point refinery wells.

Additional publication details

Publication type:

Report

Publication Subtype:

USGS Numbered Series

Title:

Historical ground-water-flow patterns and trends in iron concentrations in the Potomac--Raritan--Magothy aquifer system in parts of Philadelphia, Pennsylvania, and Camden and Gloucester Counties, New Jersey

Series title:

Water-Resources Investigations Report

Series number:

2003-4255

Edition:

-

Year Published:

2003

Language:

ENGLISH

Description:

vi, 37 p. : ill., maps (some col.) ; 28 cm.

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